One verse

Srimad Bhagavatam 10.52.31

10.52.31

सन्तुष्टो यर्हि वर्तेत ब्राह्मणो येन केनचित् । अहीयमान: स्वद्धर्मात् स ह्यस्याखिलकामधुक् ॥ ३१ ॥

santuṣṭo yarhi varteta brāhmaṇo yena kenacit ahīyamānaḥ svad dharmāt sa hy asyākhila-kāma-dhuk

santuṣṭaḥ
satisfied
yarhi
when
varteta
carries on
brāhmaṇaḥ
a brāhmaṇa
yena kenacit
with whatever
ahīyamānaḥ
not falling short
svāt
of his own
dharmāt
religious duty
saḥ
those religious principles
hi
indeed
asya
for him
akhila
of everything
kāma-dhuk
the mystic cow, milked for fulfillment of any desire

When a brāhmaṇa is satisfied with whatever comes his way and does not fall away from his religious duties, those very religious principles become his desire cow, fulfilling all his wishes.